Process for the manufacture of fertilizers and compositions



Patented Apr. 7, 1936 Walter m. r. r

ern, heterohnry, We, and heonnrrl W. hohncr, hyrnense, it... R2,asslynorn to litnnoopheric l litroyen Worporntlon, New Wort, it". W, a,corporation oi hlew Worh l lo phony. hpplicntlon lltnreh r, not,

' herlnl l lo. llihhlt o tertiliaer salts in the term. oi saidcompositions;

and the use oi these compcntions in protection of the methods tor thehrtation oi atmospheric nitropen, which have none into entensive comlilinercinlmc, make nvailahie tor indiistrinl pnrposes and particularly torthe prodnction oi tertilizers large quantities oi fixed nitrogen, in theiorrn oi ammonia. the ammonia may be industrially used as such, or itmay be oxidized to form.

oxides of nitrogen which may be absorbed in milk of lime" or in asuspension of limestone to form calcium nitrate. The oxides of nitrogenalso may be absorbed in water to form nitric acid which may then beutilized to prepare calcium nitrate and ammonium nitrate, both of whichare valuable fertilizer ingredients.

.flhe production and marketing of ammonia,

either as free ammonia or in combination as ammonium salts, and ofcalcium nitrate, is attendedby dlfllculties'and expensive operations.

Liquid anhydrous ammonia itselih a relative- 1y. high vapor pressure atordinary. mperatures.

Accordingly, in order to ship and handle the ammonia in this form,precautions must be taken to prevent losses of ammonia. In the case of'l afmmonia shipped'in the form of aqua ammonia, in large portion of thetransportation costs go for vthetransportation oi the valueless water.Furi hermiore in the preparation of ammonium nitrate and calcium nitrateby the reaction of nitro- 'g'en oxides or nitric acid with ammonia andcalcium oxide .or calcium carbonate respectively,

large amounts 0! water are used which must be 40 evaporated in' order toobtain solid salts.

Wt. ti -iii lhspecially is this nimcnit, and errpensiye in the case orcalcium nitrate, since the concentrated eolnhons at this salt areevaporated only with riimcnlty and the calcium nitrate melt ohtaineoi ina viscous press which readily snpercools heiore soliditylng and whichhas, ottersolidiiylne, the property oi avidly ahsorhine moisture fromthe atmosphere to term hydrates and or enkiny, which makes itstransportation and storage climcnlt. holirl ammonium nitrate also ishygroscopic and cakes during storage. The tendency which hoth ammoniumnitrate and calcium nitrate have to cake makes necessary the expense ofcrushing the caked salts before inc crating them with other ingredientsin making ixed fertilizers.

It is frequently desirable prepare fertilizers containing nitrogen, aswell as P205 derived from material such as superphosphate. It has heenproposed to prepare such fertilizers by treating superphosphate withammonia. When ammonia is added to a superphosphate in relatively l eamounts, lfowever, the ammonia tends ause water and citrate soluble P205in the superphosphate, both of which are considered available as plantfood, to revert to citrate insoluble P205, which is not consideredavailable to plants. There is, therefore, a limited amount of nitrogenwhich may be added as free ammonia in treatme a superphosphate withammonia or other 30 ammoniacal material. For certain purposes, however,it is desirable to have fertilizers con- Y taining more nitrogen thanmay be obtained by 'ammoniatlng superphosphate. Furthermore, it isadvantageous to have fertilizers containing ,both nitrateand ammoniacalnitrogen, since the two forms apparently complement each other invstimulating the development oi plants at different stages of growth.Where nitrate nitrogen is provided in combination with a .cation 'suchas 40 calcium the further advantage is gained that this combinationgives an alkaline tendency after application to the soil.

It is accordingly, an object of this invention to provide a compositionof matter comprising ammoniacal solutions of ammonium nitrate andcalcium nitrate and containing a relatively large proportion of totalnitrogen, and more particularly, a relatively high proportion of nitratenitrogen to ammoniacal nitrogen in the composition. It is a furtherobject of this invention to provide methods for the economical and readytransportation of fixed nitrogen in the form of ammonia and of calciumnitrate and ammonium nitrate, and a transportable package suitable forthe economical and convenient transportation of said fixed nitrogen.Another object of this invention is to provide a process for theproduction of fertilizers from superphosphate, which fertilizers containan increased proportion of nitrate nitrogen, by treating a monocalciumacid phosphate material, superphosphate or triple superphosphate, forexample, or mixtures containing the same, with'a liquid compositioncomprising ammonia, ammonium nitrate and calcium nitrate.

This invention comprises new compositions consisting of solutions ofammonium nitrate and calcium nitrate in ammoniacal liquids such asanhydrous liquid ammonia or aqua ammonia and processes for thepreparation of said ammoniacal solutions which comprises the mixing ofanhydrous or aqua ammonia with ammoniumnitrate and calcium nitrate assolids, solutions, or slurries. The invention furthermore comprisesmethods, for -'the transportation of said ammoniacal solutions in closedcontainers under their own vapor pressures and also a transportablepackage, wherein said ammoniacal solutions may be transported,comprising a closed container within which the ammoniacal solutions maybe safely and conveniently preserved and transported under their ownvapor pressures. The invention also comprises processes for theproduction of fertilizer compositions which involve treating acidicfertilizing materials with ammoniacal solutions of calcium nitrate andammonium nitrate.

In the preparation of fertilizers containing a high proportion ofnitrogen by the treatment of a superphosphate with an ammoniacalmaterial, it is important that basic ammonia is not added to thesuperphosphate in amount suflicient to cause excessive reversion ofcitrate soluble phosphate to citrate insoluble phosphate. It is furtherfrequently desirable that the ratio of nitrate nitrogen to ammoniacalnitrogen be high since the nitrate nitrogen is immediately available tothe soil, thus providing immediate fertilizing action, whereas theammoniacal nitrogen usually proportion of nitrogen combined as a salt(salt nitrogen) may be added by employing a solution of ammonium nitratein an ammoniacal liquid, but the amount of ammonium nitrate which may beadded in such a process is limited by the solubility of the salt in theamount of ammoniacal liquid which may be used without causing unduereversion of the citrate soluble phosphate. Moreover, the ratio ofnitrate nitrogen to ammoniacal nitrogen in compositions thus prepared islimited, as for instance to 0.38 when a solution of ammonium nitrate inanhydrous liquid ammonia salting out at C. or below is employed.

By treating a super-phosphate with a solution of calcium nitrate in anammoniacal liquid the amount of nitrogen which may be incorporated withthe superphosphate, without adding an excessive amount of free ammonia,may be increased by dissolving calcium nitrate in the ammoniacal liquid.The amount of total nitrogen (both salt nitrogen and free ammonianitrogen) which may be added following this procedure is also limited bythe solubility of the calcium nitrate in the amount of ammoniacal liquidwhich may be used without causing undue reversion of citrate solublephosphate. Similarly the ratio of nitrate nitrogen to ammoniacalnitrogen in ammoniacal solutions of calcium nitrate is limited by thesolubility of the calcium nitrate. For example, this ratio is not morethan 0.21 for solutions of calcium nitrate, in an ammoniacal liquidcontaining 82 parts of ammonia for every 18 parts of water, which saltout only at a temperature of 0 C. or below.

We have discovered that the solubility of calcium nitrate in ammoniacalsolutions may be materially increased by the addition of ammoniumnitrate. The resulting solutions contain a high percentage of nitrogenand more particularly a high percentage of nitrogen in salt form.Furthermore, by this means the ratio of nitrate nitrogen to ammoniacalnitrogen is increased far above the figure obtainable by the addition ofeither calcium nitrate or ammonium nitrate alone. These solutions arevaluable also due to the fact that although they contain largequantities of dissolved salt they retain the fluid condition attemperatures commonly prevailing, even in the winter time. It has beenobserved, furthermore, that the addition of ammonium nitrate toammoniacal calcium nitrate solutions tends to decrease the turbidity dueto magnesium-compounds which occurs in the ammoniacal calcium nitratesolutions. This effect reduces the possibility of the formation ofslimes of magnesium salts on the insides of containers.

These compositions are particularly adaptable to being transported andhandled, since they remain as liquids even at relatively lowtemperatures and are particularly suitable for use in the preparation ofmixed fertilizers by adding the compositions to an acidic material suchas superphosphate or triple superphosphate, since they containrelatively high proportions of combined nitrogen to the nitrogen presentas free ammonia. In the following table there are shown the compositionsof solutions in anhydrous liquid ammonia, in aqua ammonia containingsmall amounts of water, and in aqua ammonia containing about 50 per centammonia and 50 per cent water, of calcium nitrate, both with and withoutammonium nitrate, for various temperatures at which a solid phase mightsalt out from the solution.

Tatle i in solutions containing both NHiNOs and Ca(NOs)i, as comparedwith 0.4lfor solutions.

2, and/or complexes Consideration oi Table 1, lines 1 and 2, shows that,by the addition oi. aonium nitrate to a solution or calcium nitrate in.liquid ammonia containing only a small amount of water and salting outat 0, the ratio of salt nitrogen to tree ammonia nitrogen may beincreased from 0.21 to 0.00. In the case oi solutions or calcium nitratein approximately 50% aqua ammonia salting out at 0 it may he seen fromlines 7 and't that the ratio oi salt nitrogen to tree m: onia nitrogenmaybe increased from 0.4l to L00 while at the same time the addition ofammonium nitrate causes an increase in the solubility of calcium nitratein the solution oi irom 2.00 lbs. per in. to 2.28 lbs. per 11). Nil-ls.7

With regard tothe ratio of nitrate nitrogen to ammoniacal nitrogen: Thedata given in line 1 oil Table i show that the ratio oi nitrate nitrogento ammoniacal nitrogen in a solution of calcium nitrate in liquid oniacontaining a small quantity of water and salting out at 0 C. is 0.21.

- Line 2 shows that the ratio of nitrate nitrogen to ammoniacal nitrogencan be increased to 0.20

- WW pressure in the system NH4NOs-CMNO3) 2-NH3-H20 Composition weightpercent Salt Percent Pounds Pounds N g temp c t m NHaNOa CB(NO3)0 FreeN-H +NH 4 0 NH NOJ| camel). NH. mo 3%; N

' M01. ratio of cantor) to H50 approximately 112- 1 o o 45 45 at 1 0 1.0o 0. 21 o. 21 (2) 0 45. 0 16. 4 35. 0 3. 6 47. 3 1. 2i) 0. 47 0. 64 0.(3) 5. 5 10. 0 39. i 42. 0 8. 0 44. 8 0. 24 0. 94k 0. 29 (4i) 7 2 06. 08. 2 24. 0 1. 8 44. 2 '2. 75 0. 341 1. 24 (5) -2 30. 0 25. 4 39. 0 5. 646. 9 0. 77 0. 65 0. 40 (6) 0 74. 6 0 25. 4 0 l7. 0 2. 94 0 l. 0. 38

Solutions in approximately 50 percent aqua NH;

(7) 0. 0 50. 0 25. 0 25. 0 29. 1 0 2. 00 0. 41 .0. ill 8 0 25. 0 40. 017. 5 17. 5 29. 9 1. i3 2,. 28 1. 08 0. 60 9 0 03. 4 0 18. 3 18. 3 37. 33. 47 0 1. 47 0. i2 (10) 2. 5 10. 0 50. 0 20. 0 20. 0 28. 5 0. 50 2- 500. 73 (11) --3 i9. 0 13. 0 19. 0 19. 0 34L 9 i 2. 58 0. 68 1. 24

containing Ca.(N03)2 alone and 0.02 for solutions containing N31100:.alone.

The liquid comp itions or this invention present numerous practicaladvantages from the viewpoint of the marketing of nitrogenous materialsand the production of nitrogen-phosphorus fertilizers. By addition oiammonium nitrate to solutions of calicum nitrate in aqua monia, it ispossible in many cases to increase the amount of calcium nitrate whichmay be dissolved in a given quantity oi ammonia and still obtaincompositions which will not crystallize within the range of atmospherictemperatures, and the possibility of shipping and utilizing such liquidswithout any dimculty arising from crystallization makes them of especialvalue.

The presence oi ammonium nitrate and cal-- cium nitrate in anhydrous oraqua, Mm.

Table .2

0ompositlon1Wei gl1t percent Vapor pressure atm. gauge 1m NH: out temp.NHs+HzO NEhNOa 0801011): NJEla Hi0 0 C. 10? C. 20 C. C. C.

(1 0"C 0.91 45.0 16.4. 35.0 3.0 .l 1.0- 1.7 2.0 4 3.9- (2 0. 91 0 0 01 92. 7 4. i B. 6 9. 4 l3. 2 (3 0 C--..-.. 0. 61 24. 9 39. 0 17. t 0. 87-0. 79 -0. 06 0. 49 0. 23 (4) 0. 51 0 0 0. 2 0. 8 1.0 2. 75 4.2

taining small amounts of watefland saturated at 0 C., as compared with0.21 for similar eamom-mn-mo' solutions; In aqua ammonia solutions theeflect of addition ofammonium nitrate is even more-marked. Lines '7, 8and 9 indicate that for solutions of 50% aqua. ammonia, with salting outtempe 'atureof- 0 0., the ratio of 0.60 for nitrate.

nitrogen to ammoniacal nitrogen can .be attained From Table 2 line 2, itmay be seen that a liquid containing 91% ammonia and 9% water has a'vapor pressure of 2.7 atmospheres gauge at 0 C;

and 13.2 at 40" C. By the addition of ammonium nitrate and calciumnitrate to such an emmoniacal liquid in the proportions given in line iof the table, the vapor pressure of the'solution at 0 may be reduced to0.4 atmosphere gauge and at 40 to only-3.9 atmospheres gauge. The datain line 4 is for a. 51% aqua ammoniawhich has a 15 vapor pressure of 0.2atmosphere gauge at 0 and 4.2 atmospheres gauge at 40 C; Now, ifammonium nitrate and calcium nitrate be added to such a liquid in theproportions given in the table, line 3, the vapor pressure is reduced to-0.87 atmosphere gauge pressure at 0 C. and -0.23 atmosphere gaugepressure at 40 C. In other words, such a solution exerts a vaporpressure materially below atmospheric throughout the temperaturesordinarily met with.

Anhydrous liquid ammonia exerts a vapor pressure ranging from 3.2atmospheres gauge to 1&3 atmospheres gauge between 0 C. and 40 C. Bydissolving ammonium nitrate and calcium nitrate in anhydrous liquidammonia, solutions having vapor pressures materially less than the vaporpressure of the liquid ammonia may be obtained.

Thus these solutions of ammonium nitrate and calcium nitrate inanhydrous or aqua ammonia provide a convenient means for transporting,storing and handling of ammonium nitrate, calcium nitrate and ammonia,since their relatively low vapor pressures allow the use of closedcontainers in which the solutions may be stored under their own vaporpressure without the containers being subjected to high internalpressures. In some cases the pressure may be atmospheric and thepressure of the composition itself constitute only a part of the totalpressure within the container. Our invention accordingly comprises atransportable package comprising a closed container and within it aliquid composition described herein, under its own vapor pressure whichconstitutes either the whole or ,a part of the total pressure of theliquid.

The anhydrous solutions of this invention may be conveniently preparedby treating the desired proportions of dry calcium nitrate and ammoniumnitrate with gaseous or liquid anhydrous ammonia. In making aqueoussolutions, solutions, or slurries of calcium nitrate and ammoniumnitrate in water may be treated with either aqua, gaseous or liquidanhydrous ammonia, or if desired, solid, moist calcium nitrate andammonium nitrate may be dissolved in the desired strength of anhydrousliquid or aqua ammonia. Solutions or slurries of calcium nitrate andammonium nitrate having any desired degree of concentration may betreated with ammonia. Furthermore, this invention permits of producingammonium nitrate and calcium nitrate by absorbing ammonia in nitric acidsolutions or by reacting milk of lime or calcium carbonate with nitricacid or nitrogen oxides, without necessitating a close control of theprocess in order to obtain a non-acid product such as is required wherethe solid ts are to be shipped. Where the compositions f this inventionare used for the transportation and marketing of the calcium nitrate andammonium nitrate the solutions in which the ammonia is absorbed may beoperated with any desired degree of acidity or the solutions of calciumnitrate obtained by reacting calcium carbonate or calcium oxide withnitric acid or nitrogen oxides may have any desired content oi freeacid, since this acid is neutralized by the ammonia used in making upthe ammoniacal solutions of this invention.

The methods suitable for the preparation of these solutions, therefore,facilitate putting the calcium nitrate, ammonium nitrate and ammoniainto a form in which they may be moved readily to the market and provideliquid compositions which, at the usual atmospheric temperatureconditions, does not throw down a precipitate of solid material, or ifsome precipitate should occur at extremely low temperatures, such as maybe met with in the winter time, the crystallized solid may beredissolved by a slight warming of the solution. v

The use of the compositions of this invention as a means for thetransportation, storage, and

handling of calcium nitrate, ammonium nitrate and ammonia obviates thedifficulties arising in the marketing of the solid salts because of theproperty these solid salts have of caking together when stored, whichfrequently necessitates crushing of the caked mass before it may beutilized. The liquid compositions containing calcium nitrate, ammoniumnitrate and ammonia on the other hand, may be readily utilized in theproduction of fertilizer materialscontaining superphosphate, forexample, by mixing the liquid with the solid. This mixing may, ifdesired, be accomplished by spraying the liquid onto the solid materialwhile it is being agitated in a mixing machine. The liquid compositionsare suitable for spraying since they may be readily handled withouttheir clogging the sprayer by the formation of solid material from thesolution. The use of the liquid permits of a thorough dissemination ofthe calcium nitrate, ammonium nitrate and ammonia throughout thesuperphosphate material and the formation of substantially homogeneousfertilizer products having a satisfactory physical condition.

The following examples are illustrative of methods and their use in theproduction of fertilizers, but the invention is not limited to thoseexamples or to the particular details described. The amounts of thevarious materials given in the examples are in parts by weight.

Example 1.--An ammoniacal solution of ammonium nitrate and calciumnitrate such as is shown in line 2, Table 1, may be prepared by,dissolving about 45 parts of dry NH4NO3 and 20 parts of Ca(NO3)2.2H2Oin 35 parts of liquid anhydrous ammonia. A solution results which doesnot salt out at temperatures above 0 C.

Example 2.An aqueous ammoniacal solution containing ammonium nitrate andcalcium nitrate such as is shown in line 8, Table 1, may be prepared bytreating 76.7 parts of Ca(NO3) 2.4H2O with 23.3 parts of liquidanhydrous ammonia to make a solution which at 0 would form a slurry, inthe liquid part of which there would be about 2 parts of C8.(NO3)2 perpart of free NHa, and adding to every parts of this calciumnitrateammonia composition about 33.3 parts of NH4NO3. The resultingsolution does not salt out above about 0 C.

Example 3.A complete fertilizer mixture may be prepared by adding about114.5 parts of a solution having a composition approximately the same asthat described in Example 1, to a mixture containing about 890 parts ofsuperphosphate (18% P205), parts of (NH4)2SO4(21% nitrogen), parts ofsulphate of potash (50% K20) and 710.5 parts of inert filler. Theresulting mixture is in excellent physical condition immediately afterammoniation and also after cooling to atmospheric temperature. Theproduct contains 4% N (of which about 3' was derived from the solution),8% P205 and 4% &O. Approximately one-seventh of the total nitrogen inthe mixture is in the nitrate form.

Example 4.-A solution having a composition approximately the same asthat given in Example I 2 is prepared and used in the preparation of alil complete fertilizer mixture as follows. About 229 parts of thesolution are added in a suitable manner to a mixture containing 890parts of superphosphate (18% P205), 55 parts of (NHOzSOr mediately afterpreparation and also after cooling to atmospheric temperature. Theproduct contains about 4% N (of which about 85% was derived from thesolution), 8% P205, and 4% K20.

Approximately one-third of 'the total nitrogen in the mixture is in thenitrate form.

If desired additional materials, such as sodium or potassium nitrate,ammonium sulphate, am-.

monium phosphate, urea, etc, or any two, or more of these materials,which in themselves are valuable fertilizers, may be incorporated withthe ammoniacal solutions of this invention before they are added to thephosphate material, or these added materials may be incorporated with aphosphate, material before, after or simultaneously with the treatmentwith the ammoniacal solution. in preparing the fertilizers of thisinvention, the several solid ingredients may if desired, beintroducedinto a mixer and simultaneously admixed therein with theammoniacal solution which is preferably supplied as a spray to thematerials while they are being admixed. l urther, if desired, thesuperphosphate material may be ammoniated with the ammoniacal S0111?tion and this ammoniated material used as a tertilizer itself or it maybe admired with one or more additional fertilizer ingredients. Thephrase "saturated with solid components? at a given temperature as usedherein, refers to solutions of ammonium nitrate and calcium nitrate,

from which a solid material containing calcium nitrate and/or ammoniumnitrate (either of which may be in the solid form in combination withother components of the soluti Particularly the ammonia) separates outfrom the solution I when it is cooled to a. lower temperature.

We claim:

l. as a new composition of matter, a solution,

of ammonium nitrate and calcium nitrate in an ammoniacal liquid, saidsolution containing a substantial proportion of ammonia. andbeingsubtill " of ammonium nitrate and calcium nitra.

stantially saturated with the aforesaid solid com- I ponents at atemperature between about til C. to 30 ill.

2. As a new composition of matter a solution of ammonium nitrate andcalcium nitrate in an ammoniacai liquid, said solution containing asubstantial proportion of ammonia and being substantially saturated withthe aforesaid solid components at a temperature of about 0 C.

3. As a new composition of matter a solution in anhydrous liquid ammoniasubstantiallly saturated with the "aforesaid solid components at about--so c. to core.

4. As a new composition of matter a solution of ammonium nitrate andcalcium nitrate in aqueous ammonia, said solution containingasubstantial proportion of ammonia and being substantially saturatedwith the aforesaid solidcomponents at about -30 C. to 30 C. u v

5, As a new composition of matter a solution of ammonium nitrate andcalcium nitrate in 50% aqueous ammonia. substantially saturated with theaforesaid solid components at about 0 C.

" "i*6r-Asanew composition of matter a solution of ammonium nitrate andcalcium nitrate in aqueous ammonia, said solution containing a 811)!stantial proportion of ammonia and being substantially saturated withthe aforesaid solid com ponents at about 0? C. and containing about 2.5

parts of calcium nitrate per part of free ammonia.

a new composition of matter a solution of ammonium nitrate and calciumnitrate in aqueous ammonia, said solution containinga sub stantialproportion of ammonia and being substantially saturated with theaforesaid solid components at 0 i3. and containing about 37% of thetotal nitrogen in the form of nitrate nitrogen.

8.' The process for the preparation for transportation of ammonia andcalcium nitrate which comprises mixing said ammonia and calcium nitrateand ammonium nitrate to form a liquid product which contains asubstantial proportioncomprises treating a'superphosphate material with,a liquid composition containing about to parts of ammonium nitrate,about 20 parts of calcium nitrate in about do'parts of substantiallyanhydrous l onia, said solution being added to the superphosphatematerial in the proportion of about lloparts of the solution to about890 parts supcrphosphate.

11. A process for producing a fertilizer which comprises treating asuperphosphate material with a liquid composition containing about 92parts Ca (N03) 2, about or parts NHiNOEl, about to parts ammonia andabout to parts water, said composition being added to the superphosphatematerial in the proportion of about 229 parts of solution to about oneparts of superphosphate material.

12. it. process for producing a fertilizerwhich comprises treating asolid acidic fertilizing material with an ammoniacal solution of calciumnitrate and ammonium nitrate, said solution containing a substantialproportion of ammonia and being substantially saturated with theaforesaid.

solid components peratures. I

13. A process for producing a fertilizer which comprises treating asuperphosphate material with a solution of calcium nitrate and ammoniumat ordinary atmospheric temnitrate in 50% aqua ammonia, saidsolution'prior portation of ammonia and calcium nitrate which comprisesmixing about 50% aqua ammonia with calcium nitrate and ammonium nitrateto form a liquid containing dissolved calcium nitrate in excess of thatrequired for saturation of the aqua ammonia in the absence of theammonium nitrate.-

bit

till

comprises treating a superphosphate with a solution of calcium nitrateand ammonium nitrate in about 50% aqua ammonia, said solution containingan amount'of calcium nitrate dissolved therein in excess of that solublein said aqua 5 ammonia in the absence of ammonium nitrate.

WALTER H. K'NISKERN. LEONARD v. ROHNER.

